Crystal Growth & Design最新文献

Five new quaternary thioarsenates/thioantimonates KHgAsS₃ (1), Rb₃Ag₉As₄S₁₂ (2), RbAg₂SbS₃ (3), Rb₂HgSbS₃(SH) (4), and Cs₂HgSbS₃(SH) (5) were successfully obtained by the solvothermal method via excess sulfur as a mineralizer. The five synthesized sulfides exhibit different dimensions, including one-dimensional (4, 5), two-dimensional (1, 3), and three-dimensional (2). In their anionic structures, the transition metal ions (Ag⁺/Hg²⁺) adopt different coordination modes (AgS₃, AgS₄, and HgS₄), and there exist different rings (6-, 8-, and 10-membered rings). The results of the UV–vis diffuse reflection experiment and theoretical calculation show that all the compounds are semiconductors. The experiments display that compound 4 exhibits relatively obvious photocatalytic degradation effect of methylene blue (MB) and displays a certain photoelectric response signal.

This paper explores the development and testing of a simple absorption correction model for processing powder X-ray diffraction data from Debye–Scherrer geometry laboratory X-ray experiments. This may be used as a preprocessing step before using PDFgetX3 to obtain reliable pair distribution functions (PDFs). Various experimental and theoretical methods for estimating μR were explored, and the most appropriate μR values for correction were identified for different capillary diameters and X-ray beam sizes. We identify operational ranges of μR where a reasonable signal-to-noise ratio is possible after correction. A user-friendly software package, diffpy.labpdfproc, is presented that can help estimate μR and perform absorption corrections with a rapid calculation for efficient processing.

All uniform and continuous wafer-scale sp²-hybridized boron nitride (sp²-BN) is one of the most promising candidate materials for vacuum ultraviolet photodetectors (VUV PDs). However, the fabrication of large-area, high-efficiency sp²-BN VUV PDs remains challenging. This study systematically investigates the role of high-temperature annealing-assisted metal–organic chemical vapor deposition (MOCVD) in enhancing thin-film quality and device performance. Through optimized annealing treatment, we achieved significant improvements in the crystalline uniformity of sp²-BN films and reduced dislocation density. Raman, FTIR, and XRD analyses consistently showed a narrowed full-width-at-half-maximum (FWHM) of characteristic peaks, while TEM cross-sectional imaging confirmed enhanced structural ordering. Mechanistic studies revealed that during annealing, nitridation of the sapphire substrate generated AlN interlayers, which guided the epitaxial rearrangement of BN molecules along the AlN crystallographic planes, thereby promoting defect annihilation. Device characterization demonstrated remarkable performance enhancements: response time (τ_r/τ_d) decreased from 356.16/142.27 ms to 39.34/41.34 ms, responsivity increased by 193% to 0.79 mA/W, and detectivity improved by 267% to 3.45 × 10¹⁰ Jones. This work establishes high-temperature annealing-assisted MOCVD as an effective strategy for optimizing sp²-BN VUV PDs, providing a viable pathway for advanced ultraviolet detection applications.

Designing and realizing high-performance p-type transparent conductive oxide films represent a global materials challenge. Mg-doped CuCrO₂ delafossite has emerged as an ideal candidate for p-type transparent conductive oxides due to its balanced combination of favorable optical transmittance and electrical conductivity in the visible region. In this study, epitaxial CuCr_1–xMg_xO₂ (x = 0, 0.01, 0.03, 0.05, 0.07, 0.09) thin films were successfully fabricated on Al₂O₃ substrates using chemical solution deposition. We systematically investigated the effects of the Mg doping concentration on crystal structure, surface morphology, electrical transport properties, and optical transmittance. The results demonstrate that high-quality epitaxial growth was confirmed by X-ray diffraction (XRD) and φ-scan analysis. Mg doping synergistically regulates optoelectronic properties by introducing acceptor levels─resistivity decreased by orders of magnitude with increasing doping concentration, attributed to significantly enhanced hole carrier concentration. Concurrently, the optical bandgap progressively narrowed, with UV–vis–NIR spectroscopy confirming continuously tunable direct bandgap characteristics. This work elucidates the physical mechanism governing optoelectronic property modulation in epitaxial CuCr_1–xMg_xO₂ thin films, advancing both the development of epitaxial delafossite thin film fabrication techniques and further applications in transparent electronics.

While calcium carbonate is well known to exist in a range of different crystalline forms, including anhydrous polymorphs and hydrated phases, a new crystalline form─calcium carbonate hemihydrate (CCHH)─was reported in 2019 and has recently been observed in a biogenic material. The crystal structure of CCHH reported from diffraction studies is monoclinic, although a subsequent computational investigation suggested that an orthorhombic description of the structure may be more appropriate. Herein, we report experimental solid-state NMR characterization of CCHH, focused on solid-state ¹H NMR and ¹³C NMR measurements, including analysis of ¹H–¹³C heteronuclear correlation spectroscopy (HETCOR) and ¹³C chemical shift anisotropy (CSA) data, which reveals further insights into the structural and symmetry properties of this material. We demonstrate by means of DFT-GIPAW calculations that the monoclinic and orthorhombic descriptions of the crystal structure of CCHH are readily distinguishable on the basis of solid-state ¹H and ¹³C NMR data. Our experimental solid-state NMR measurements are shown to support the orthorhombic description of the crystal structure rather than the monoclinic description.

Two crystalline polymorphs of a conjugated organic fluorophore were obtained through separate synthetic protocols despite crystallizing under identical conditions. The unique polymorphs were confirmed by single-crystal X-ray diffraction. The two polymorphs had markedly different supramolecular packing. Thus, polymorph A was stabilized by directional C–H···N/S interactions with limited π overlap, while polymorph B assembled into extended π–π stacks and a denser network with short contacts. These structural differences resulted in distinct photophysics. Indeed, the emission quantum yield (Φ_fl) of Polymorph B was 4-fold lower along with multiexponential excited state kinetics compared to Polymorph A in addition to a 38 nm blue-shift in the emission. The metastable polymorph B could be converted to the thermodynamically stable Polymorph A by grinding the pristine crystal. Both intra- and supramolecular contacts could be leveraged to guide the crystal packing for modulating the emissive properties of the intrinsic fluorophores.

Precise regulation of metal cluster structures and luminescent properties is critical for the advancement of their practical applications. Copper clusters have garnered extensive attention due to their abundant, inexpensive, and excellent luminescent properties. However, their strong metallophilic interactions often restrict emissions to the red region, making it challenging to controllably tune their emission range─especially toward high-energy bands. In this work, we propose a counterion-induced strategy to modulate the structure and luminescence properties of copper clusters. By adjusting the size of counter cations, we induced varying degrees of distortion in Cu₅ anionic cluster structures and directed their crystallization into distinct assembly patterns, successfully obtaining four cluster-based luminescent materials. Theoretical calculations reveal that under the steric effects of counter cations, the four Cu₅ clusters exhibit different molecular configurations and intercluster interaction strengths, enabling broad-range emission wavelength modulation (546 → 687 nm). Notably, Cu₅-Pr-a and Cu₅-Et demonstrate unconventional high-energy emissions. This study provides a novel approach and experimental reference for the precise control of metal cluster structures and luminescent properties.

Poly(lactic acid) (PLA) porous materials hold great promise for biomedical applications such as tissue engineering and drug delivery. However, achieving precise control over their pore architecture remains challenging due to the complex interplay between phase separation and crystallization. This study investigates the temperature-directed competition among cocrystallization, homocrystallization, and stereocomplex (SC) crystallization in PLA/dimethylformamide (DMF) systems during thermally induced phase separation (TIPS). By quenching PLLA/PDLA solutions with varying ratios over a wide temperature range (−20 to 30 °C), we demonstrate that the final morphology, which ranges from three-dimensional nanofibrous networks to well-ordered lamellae or monodisperse microspheres, is intricately governed by the dominant crystallization pathway. At lower temperatures, the formation of PLA–DMF ε-complex crystals templates a nanofibrous structure upon solvent removal. In contrast, at elevated temperatures, SC crystallization is exclusively promoted in equimolar blends, resulting in coarse spherical particulates. Furthermore, the morphology and microstructure are found to influence the thermal stability and enzymatic hydrolysis rate of the PLA porous materials, without inducing cytotoxicity. These findings provide deeper insight into the crystallization-phase separation interplay in PLA systems and establish a versatile strategy for fabricating PLA-based materials with tailored morphologies to meet specific biomedical requirements.

The crystal growth of two families of lanthanide zirconium molybdates exhibiting luminescence properties is reported. Crystals of Ln₂Zr₃(MoO₄)₉ (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd) and Ln₂Zr₂(MoO₄)₇ (Ln = Tb, Dy) were obtained by the molten flux growth technique. Ln₂Zr(MoO₄)₅ (Ln = Ho, Er, Tm, Yb, Y) were synthesized by solid-state reactions. The compounds Ln₂Zr₃(MoO₄)₉ (Ln = La- Nd, Sm–Gd) crystallize in the space group R3̅c with lattice parameters of a = b = 9.85200(10)–9.78700(10), c = 59.1112(9)–57.9131(10) Å. The second class of compounds Ln₂Zr₂(MoO₄)₇ (Ln = Tb, Dy), crystallize in the space group C2/c with lattice parameters of a = 20.7457(4)–20.7015(4) Å, b = 9.8556(2)–9.8395(2) Å, c = 13.8424(3)–13.8261(2) Å, and β = 113.5210(10)–113.5440(10)°. The third class of compounds, Ln₂Zr(MoO₄)₅ (Ln = Ho, Er, Tm, Yb, Y), crystallizes in the space group Cmc2₁ with lattice parameters of a = 21.031(2)–20.824(4) Å, b = 9.7473(5)–9.6540(2) Å, and c = 9.7961(9)–9.l7420(2) Å. The structures consist of frameworks where LnO₉ and ZrO₆ polyhedra are connected with MoO₄ groups via corner-sharing. Solid-state reactions were used to make bulk polycrystalline samples for property measurements. Optical properties of Ce₂Zr₃(MoO₄)₉, Sm₂Zr₃(MoO₄)₉, Eu₂Zr₃(MoO₄)₉, and Tb₂Zr₂(MoO₄)₇ were investigated. In addition, the magnetic properties of Ce₂Zr₃(MoO₄)₉, Sm₂Zr₃(MoO₄)₉, Gd₂Zr₃(MoO₄)₉, and Tb₂Zr₂(MoO₄)₇ are reported.

Ionic liquids (ILs) represent an extensively studied class of materials. Nevertheless, their solid state has often been overlooked, leading to frequent knowledge gaps about their phase behavior or crystal structures that such materials may form. This work focuses on the development of a crystal structure prediction (CSP) scheme suitable for aprotic ILs, relying on quasi-random crystal structure generation, dispersion-corrected density functional theory (DFT-D)-based energy reranking, and quasi-harmonic phonon treatment. The interpretation of peculiar differences in the crystallizability of very similar ILs upon cooling of their melts is presented. The versatility of the computational protocol is validated for [emIm][MeSO₃], an IL known to be polymorphic. The current CSP identifies the [emIm][MeSO₃] polymorph that is thermodynamically stable in reality at the top of the stability ranking, both in terms of DFT-D refined lattice energies and quasi-harmonic Gibbs free energies. Several low-energy, high-entropy crystal structures are also proposed for [emIm][MeSO₃] as candidates for the remaining known polymorphs with yet unresolved crystal structures. Our CSP modeling explains the extraordinary reluctance of [emIm][EtSO₄] to crystallize due to its glassy shape of the polymorph landscape with no distinct global energy minimum crystal structure.